Download guidelines for the use of radiographs in clinicalorthodontics

GUIDELINES
FOR THE USE OF
RADIOGRAPHS IN
CLINICAL ORTHODONTICS
X
K G Isaacson
Emeritus Consultant Orthodontist
A R Thom
Emeritus Consultant Orthodontist
N E Atack
Consultant Orthodontist
Bristol Dental Hospital, Bristol
K Horner
Professor of Oral and Maxillofacial Imaging
School of Dentistry, Manchester
E Whaites
Senior Lecturer/Honorary Consultant in Dental Radiology
King's College London Dental Institute, London
British Orthodontic Society
Fourth Edition 2015
© Copyright British Orthodontic Society
The right of Isaacson, Thom, Atack, Horner and Whaites to be identified
as authors of this work has been asserted by them in accordance with the Copyright
Designs and Patents Act 1988. No part of this publication may be reproduced in any
material form without the written permission of
the copyright owner except in accordance with the provisions of the
Copyright Designs and Patents Act 1988.
Publishers and Copyright owners:
British Orthodontic Society
12 Bridewell Place, London EC4V 6AP
Tel: +44 (0)20 7353 8680
Fax: +44 (0)20 7353 8682
www.bos.org.uk
British Library Cataloguing Data
A catalogue record for this book is available from the British Library
ISBN 1 899297 09 X
1
CONTENTS
PAGE
1. FOREWORD
FOREWORD
2
2. PREFACE TO THE FOURTH EDITION
3
3. INTRODUCTION
3
4. THE DAMAGING EFFECTS OF IONISING
RADIATION
4
5. THE AIMS OF RADIATION PROTECTION
4
6. UK LEGISLATION RELATING TO
THE USE OF IONISING RADIATION
5
7. RADIATION DOSE DELIVERED BY DIAGNOSTIC
IMAGING AND THE MAGNITUDE OF THE
RISKS INVOLVED
6
8. IMAGING EQUIPMENT AND TECHNIQUES
AVAILABLE FOR ORTHODONTIC RADIOGRAPHY
8
9. METHODS OF RADIATION PROTECTION
INCLUDING QUALITY ASSURANCE
11
10. SELECTION CRITERIA FOR THE USE OF
RADIOGRAPHS IN ORTHODONTICS
14
11. APPLICATION OF CONE BEAM COMPUTED
TOMOGRAPHY IN ORTHODONTICS
22
12. RADIOGRAPHY IN ORTHODONTIC
TEACHING, RESEARCH AND AUDIT
24
13. IMAGING OF THE
TEMPOROMANDIBULAR JOINT
25
14. MEDICOLEGAL ASPECTS OF RADIOGRAPHY
FOR ORTHODONTIC PURPOSES
26
15. CONCLUSIONS
27
16. GLOSSARY
28
IN 1994 The British Society for the Study of Orthodontics
(BSSO) asked the Standards Committee to develop guidelines
for the use of radiographs in orthodontics, which formed the
basis for the first edition. This was one of the first published sets
of guidelines for dentistry. The initial work done by the members
of the Committee has been the basis for further editions. In 2000
the Ionising Radiation (Medical Exposure) Regulations (IRMER)1
were published and these were incorporated into the
subsequent editions.
The need for a fourth edition is due to the increasing availability
of Cone Beam Computed Tomography (CBCT) which usually
enables dento-maxillofacial imaging with a lower exposure than
conventional CT. Such machines are now readily available and
are being promoted as 3D imaging techniques for the teeth and
jaws. Some orthodontists are using them as part of orthodontic
treatment planning and, although the exposure is usually less
than a conventional CT, it can be at least 20 times greater than
normal dental radiography.2
CBCT imaging has a useful place in selected cases and European
evidence-based guidelines for their use have been formulated by
the SEDENTEXCT project.3 In this edition a new section on CBCT
has been added which takes these European guidelines into
account and discusses their place in orthodontic treatment.
The majority of changes in this fourth edition are due to the
expertise of the dental and maxillofacial radiologists
Keith Horner and Eric Whaites.
Keith G Isaacson
ACKNOWLEDGEMENTS
With acknowledgements for assistance to:
Mr Tim Jones and Mrs Mandy Payne for editorial services.
Mr Nigel Pearson of Guy’s and St Thomas’ Hospital
Photographic Department; and Miss Felicity Whaites,
our photographic model. Mr John Sorrell for design
and production.
PUBLIC HEALTH ENGLAND (PHE)
John Holroyd of PHE Dental X-ray Protection Services for
permission to reproduce figure 2 and material from
Guidance Notes for Dental Practitioners on the Safe Use
of X-ray Equipment (2001), Department of Health.
ELSEVIER
for permission to reproduce material from
Essentials of Dental Radiography and Radiology
5th Edition (2013), Whaites & Drage.
2
The British Orthodontic Society is indebted to the
authors who have waived their entitlement to the
royalties arising from the sale of these Guidelines.
1. Health and Safety Legislation (2000) 3. European Commission (2012)
The Ionising Radiation (Medical
Cone beam CT for dental and
maxillofacial radiology (EvidenceExposure) Regulations 2000. SI 2000
based guidelines). Radiation
No 1059. London, the Stationery
Office (IRMER)
Protection no 172. Luxembourg:
http://www.legislation.hmso.gov.uk/si/
Publications Office
si2000/20001059.htm
http://www.sedentexct.eu/files/
2. Larson BE (2012)
radiation_protection_172.pdf
Cone-beam computed tomography is
the imaging technique of choice for
comprehensive orthodontic assessment.
American Journal of Orthodontics and
Dentofacial Orthopedics 141, 402
2
PREFACE TO THE FOURTH EDITION
THE purpose of guidelines is to improve the effectiveness, and
efficiency, of clinical care.4 To serve a useful purpose they must be
reviewed regularly. Despite the availability of these guidelines the
practice of taking routine orthodontic radiographs for children as a
matter of course, often before a clinical examination, persists.5
This puts these children at unnecessary risk.
These guidelines are designed to assist the general practitioner,
the orthodontic specialist and the hospital practitioner on the
choice and timing of radiographs in clinical orthodontic practice.
The existence of guidelines does not mean that compliance is
necessary and non-compliance does not equate with negligence.6
They are recommended as current best practice and as selection
criteria to comply with the requirements of IRMER.1
REVIEW OF THE FOURTH EDITION
“In The Wealth of Nations, Book I, Chapter X, Adam Smith noted
that, ‘People of the same trade seldom meet together, even for
merriment and diversion, but the conversation ends in a conspiracy
against the public, or in some contrivance to raise prices.’ In the
present 4th Edition of Guidelines for the Use of Radiographs in
Clinical Orthodontics, the authors with the British Orthodontic
Society have conspired instead to protect the public from needless
and costly exposure to ionizing radiation. Given the reluctance of
many societies to go beyond platitudes when it comes to
specifying professional standards, this edition of Guidelines
probably will become the de facto benchmark in the world of
orthodontics. Well done, indeed!”
Lysle E Johnston Jr, DDS, MS, PhD, FDS RCS(Eng)
3
INTRODUCTION
X-RAYS, and their ability to penetrate human tissue to create
a visual image, were discovered by Wilhelm Röntgen in 1895.
Within weeks of their discovery the first dental radiographic
images were created. Within months medical diagnostic
imaging had been revolutionised. These early images required
high doses of radiation and very soon local side-effects such as
skin reddening, hair loss and ulceration became apparent.
Within only a few years it was realised that these diagnostically
useful ‘magic rays’ could also cause cancer and genetic harm.
In 1921 the first formal recommendations on radiation
protection in the UK were made by the British X-ray and
Radium Protection Committee. In 1928 The International
Commission on Radiological Protection (ICRP) was established.
The ICRP is still in existence and regularly publishes reports and
recommendations on radiation protection which are accepted
as the basis for national legislation by almost every country in
the world to try to limit the damaging effects of ionising
radiation. As a result, the use of ionising radiation in clinical
practice is governed by law – criminal law – in the UK.
Ionising radiations, including X-rays, are dangerous and have
the potential to cause damage to human tissue, including fatal
malignant change. Radiographic examinations put patients at
risk. Children are at the greatest risk. The legislation is
designed to protect patients by ensuring that all radiographic
procedures are necessary, appropriate and as safe as possible
so that patients are not placed at unnecessary risk.14 UK law
requires that all radiographs must be clinically justified.
These guidelines are primarily designed to assist orthodontists
in this ‘justification’ process.15
REVIEWS OF THE THIRD EDITION
“Perhaps the AAO might be inspired to publish a more meaningful set
of radiographic guidelines after the exceptional example set by their
British colleagues.” 7
“I was impressed with the sensible approach taken, based on published
science… I do believe the BOS points us in a direction that could result
in more ideal care for our patients.” 8
“Of importance, however, are the patient selection criteria which provide
acceptable and, hopefully, non-contestable reasons for routine
orthodontic radiographs and when those radiographs might be taken.” 9
“Overall this is an excellent book and has been updated very well.
It remains essential reading to any orthodontist or member of the
orthodontic team.” 10
“The stated aims of this excellent booklet to assist the orthodontist
to achieve sound clinical practice with desired outcomes are
successfully met.” 11
“The logical structure provides an easy expeditious read.”12
“You have always been ahead of us in areas like this... particularly clinical
guidelines... I can only hope that those involved... will take heed of
meaningful guidelines such as those in the United Kingdom.”13
Awarded ‘Highly Commended’ in the British Medical
Association Medical Book Competition 2009.
8. Turpin DL (Editor) (2008)
6. Batchelor P (2000)
British Orthodontic Society
The legal and ethical implications
revises guidelines for clinical
of evidence-based clinical
radiography
guidelines for clinicians
American Journal of Orthodontics
Evidence-Based Dentistry 2, 5-6
and Dentofacial Orthopedics
7. Gander DL (2002)
134, 597-8
5. Jerrold L (2014)
Dentomaxillofacial Radiology
9. Dreyer C (2008)
31, 211
Seeing before doing
Orthodontic radiographs
American Journal of Orthodontics
Guidelines, 3rd edition
and Dentofacial Orthopedics
146, 530-3
European Journal of Orthodontics
30, 669-70
4. Scottish Intercollegiate
Guidelines Network (SIGN)
(2000)
Getting validated guidelines into
local practice.
http://www.sign.ac.uk/
14. Hawkes N (2007)
10. Drage N (2008)
Journal of Orthodontics 35, 290-1
Scan or scandal.
The Times (Times 2) June 14,
11. Cameron J (2009)
page 4
Australian Orthodontic Journal
25, 183
12. Williams G (2009)
British Dental Journal 206, 3
13. Jerrold L (2015)
Author’s response
American Journal of Orthodontics
and Dentofacial Orthopedics
147, 296
15. Isaacson KG, Thom AR (2015)
Orthodontic radiography
guidelines
American Journal of Orthodontics
and Dentofacial Orthopedics
147, 295-6
3
4
5
THE DAMAGING EFFECTS OF
IONISING RADIATION
THE AIMS OF RADIATION
PROTECTION
THE different damaging effects on human tissue are
currently divided into two major categories:
THERE are two overall guiding aims in radiation protection:
• Tissue reactions (deterministic effects)
• Stochastic effects, subdivided into:
• Cancer induction
• Heritable effects (genetic effects).
Stochastic effects are the chance or random effects, governed by
the laws of probability, that patients may develop from any dose
of radiation. In dental X-ray imaging, the risk of heritable
(genetic) effects is considered negligible, so the stochastic effect
of concern is the risk of cancer induction. For this, the ICRP
continues to support the so called ‘Linear Non-Threshold’ model
which is based on the principle of no known threshold dose.
In other words, any exposure to ionising radiation carries the
possibility of causing damage including cancer induction.
The likelihood of any damage being induced (the risk) is
proportional to the dose. The lower the dose, the lower the
risk. However, it is very important to remember that the size
of the exposure does not affect the severity of the damage
induced. If, during low dose orthodontic radiography, cancer
induction occurs, the cancer that subsequently
develops could be fatal.
• To prevent the tissue reactions (deterministic effects) by
having rules and guidelines based on scientific evidence
• To limit the stochastic effects to acceptable levels.
Orthodontists, like all clinicians, have the responsibility of
deciding what a justifiable level of risk is for their patients.
One of the guiding principles of the ICRP in determining an
‘acceptable’ level of risk, is that of ‘justification’ – no practice
shall be adopted unless its introduction produces a net positive
benefit – and this is re-enforced in the UK legislation which
states that ‘No person shall carry out a medical exposure
unless it has been justified …’
The importance of radiation protection in dentistry has
been underlined by the publication of:
• The Guidance Notes for Dental Practitioners on the Safe
Use of X-ray Equipment published by the Department of
Health and the Health Protection Agency in 200116
• The European Guidelines on Radiation Protection in
Dental Radiology – the safe use of radiographs in dental
practice in 2004 17
• The third edition of Selection Criteria for Dental
Radiography published by the Faculty of General Dental
Practice (UK) 2013 18
• The Guidance on the Safe Use of Dental Cone
Beam CT (Computed Tomography) Equipment by the
Health Protection Agency in 2010 19
• Radiation Protection: Cone beam CT for dental and
maxillofacial radiology – guidelines published by the
SEDENTEXCT European Consortium in 2012.20
16. Department of Health (2001)
Guidance Notes for Dental
Practitioners on the Safe Use of
X-ray Equipment
https://www.gov.uk/government/
publications/dental-practitionerssafe-use-of-x-ray-equipment
17. European Commission (2004)
European Guidelines on Radiation
Protection in Dental Radiology.
Radiation Protection 136.
Luxembourg: Publications Office
https://ec.europa.eu/energy/sites/
ener/files/documents/136.pdf
4
18. Horner K, Eaton K (eds) (2013)
Selection Criteria for Dental
Radiography (3rd edition). Faculty
of General Dental Practice (UK)
19. HPA Working Party on Dental
Cone Beam CT Equipment (2010)
Guidance on the Safe Use of Dental
Cone Beam CT (Computed
Tomography) Equipment.
Chilton: Health Protection Agency
https://www.gov.uk/government/
uploads/system/uploads/attachment_
data/file/340159/HPA-CRCE-010_
for_website.pdf
20. European Commission (2012)
Cone beam CT for dental and
maxillofacial radiology (Evidencebased guidelines). Radiation
Protection no 172. Luxembourg:
Publications Office
http://www.sedentexct.eu/files/
radiation_protection_172.pdf
ORTHODONTIC RADIOGRAPHS
6
UK LEGISLATION RELATING TO THE
USE OF IONISING RADIATION
THERE are currently two sets of legislation in the UK, based on
European Directives and following ICRP recommendations, namely:
• The Ionising Radiations Regulations 1999 (IRR 99)
21
which
are primarily concerned with the safety of workers and the
general public, and
• The Ionising Radiation (Medical Exposure) Regulations 2000
(IRMER 2000) which are concerned with the protection of
patients.22
The European Commission has also published guidelines.17
The legal requirements of IRR 99 and IRMER 2000, together with
‘good practice’ advice were included in the 2001 Department of
Health booklet Guidance Notes for Dental Practitioners on the Safe
Use of X-ray equipment 16 and in 2010 in the Health Protection
Agency’s booklet Guidance on the Safe Use of Dental Cone
Beam CT (Computed Tomography) Equipment.19
ESSENTIAL LEGAL REQUIREMENTS OF IRR 99
• The Health and Safety Executive must be notified of the
routine use of dental X-ray equipment
• A prior risk assessment must be undertaken before
radiography commences and be subject to regular review
• There is an over-riding requirement to restrict radiation
doses to staff and other persons to levels that are as low as
reasonably practicable (ALARP)
• X-ray equipment, particularly all safety features,
must be maintained
• Contingency plans must be provided in the Local Rules
• A Radiation Protection Adviser (RPA) must be consulted
• Information, instruction and training must be provided
for all staff
• A ‘controlled area’ should be designated around each
piece of X-ray equipment
• Local Rules are required
• A Radiation Protection Supervisor (RPS) must be appointed
• A quality assurance programme is required
• All employees should be aware of their specific duties
and responsibilities.
ESSENTIAL LEGAL REQUIREMENTS OF IRMER 2000
• Positions of responsibility are defined:
The
The
The
The
Employer (Legal Person)
Referrer
Practitioner
Operator
• IRMER Employers are responsible for providing the overall
safety and radiation protection framework and for ensuring that
staff and procedures conform with the regulations, and for
providing ‘Written Procedures’ for all medical exposures
• IRMER Referrers are responsible for supplying the IRMER
Practitioner with sufficient information to justify an
appropriate exposure
• IRMER Practitioners are clinically responsible for, and must
justify, all medical exposures. Justification must be based
on consideration of:
The
The
The
The
specific objectives of the exposure
total potential benefit to the patient
anticipated detriment to the patient
efficacy, benefits and risks of alternative techniques
• The ‘justification’ process is the responsibility of the IRMER
Practitioner – the medical or dental practitioner who takes
responsibility for an individual medical exposure. All general
dental practitioners and specialist orthodontists in practice
are IRMER Practitioners and are therefore required by law
to justify every radiograph that they take. In hospitals,
orthodontists are IRMER Referrers if they refer their patients
to an X-ray department to be imaged. As such they are
responsible for supplying sufficient clinical information so that
the IRMER Practitioner within the X-ray department can justify
the exposures. These legal implications are one of the reasons
the General Dental Council in 2006 included ‘radiography and
radiation protection’ as one of their three essential subjects
in Continuing Professional Development (CPD). IRMER
Operators are responsible for conducting any practical
aspect of a medical exposure including exposing the
radiograph or processing the image
• IRMER Operators and IRMER Practitioners must
have received adequate training
• IRMER Operators and IRMER Practitioners must
undertake continuing education.
Dental care professionals (DCP’s) involved in taking orthodontic
radiographs are designated as IRMER Operators and therefore
must be adequately trained. Since May 2005, dental nurses
who undertake radiography have been required to possess a
post-qualification Certificate in Dental Radiography.
In addition there are essential legal requirements
regarding equipment:
• All doses must be kept as low as reasonably
practicable (ALARP)
21. Health and Safety Legislation
(1999)
The Ionising Radiations
Regulations 1999. SI 1999
No 3232. London, the Stationery
Office (IRR 99)
http://www.legislation.hmso.gov.
uk/si/si1999/19993232.htm
22. Health and Safety Legislation
(2000)
The Ionising Radiation (Medical
Exposure) Regulations 2000.
SI 2000 No 1059. London, the
Stationery Office (IRMER)
http://www.legislation.hmso.gov.
uk/si/si2000/20001059.htm
• Provision must be made for clinical audit
• An equipment inventory must be kept
and maintained.
5
7
RADIATION DOSE DELIVERED BY
DIAGNOSTIC IMAGING AND THE
MAGNITUDE OF THE RISKS INVOLVED
RADIATION dose is complicated by the fact that several
different measurements of ‘dose’ exist. The main terms are:
•
•
•
Absorbed dose (D)
Equivalent dose (HT)
Effective dose (E)
The effective dose (E) from an individual clinical radiograph,
where the beam is absorbed by different tissues, is calculated
as follows:
Effective dose (E) = ∑ Equivalent dose (HT) in each
tissue x relevant tissue weighting factor (wT)
ABSORBED DOSE (D)
This is a measurement of the amount of energy absorbed
from the X-ray beam per unit mass of tissue. It is measured in
Joules/kg. The special name given to the Standard International
(SI) Unit is the gray (Gy).
EQUIVALENT DOSE (HT)
This is a measurement of radiation dose that takes into account
the radiobiological effectiveness of different types of radiation on
different tissues. Each type of radiation is allocated a different
radiation weighting factor (wR). X-rays and gamma rays have a
weighting factor of 1, while the more damaging protons and
alpha particles have weighting factors of 10 and 20 respectively.
The Standard International unit is also the sievert (Sv).
Doses delivered by most medical radiographic techniques
are only fractions of a sievert, and are usually expressed
as µSv (micro sievert – one millionth of one sievert) or
mSv (milli sievert – one thousandth of one sievert). The
effective dose measurement can be used to compare doses
from other investigations of other parts of the body.
From an orthodontic point of view skin, bone, bone marrow,
thyroid and salivary glands are the tissues of particular
importance when radiographing children and calculating
the effective dose (Figure 1).23, 24
The equivalent dose in a particular tissue (HT) is calculated by
multiplying the radiation-absorbed dose (D) the amount of
energy absorbed by the tissue, by the radiation weighting factor
(wR) for the type of radiation being used. It is again measured in
Joules/kg and the special name of the SI unit is the sievert (Sv).
EFFECTIVE DOSE (E)
This is a measurement which allows doses from investigations of
different parts of the body to be compared, by converting all
doses into an equivalent whole body dose. The ICRP has
allocated each tissue a numerical value, known as the tissue
weighting factor (wT), based on its radio-sensitivity. The sum of
the individual tissue weighting factors represents the weighting
factor for the whole body. The recommendations of the ICRP in
2007 for tissue weighting factors are shown in Table 1.23
TABLE 1: Recommendations of the ICRP (2007) for tissue weighting factors 23
Tissue
BONE MARROW
BREAST
COLON
LUNG
STOMACH
BLADDER
OESOPHAGUS
GONADS
2007 wT
0.12
0.12
0.12
0.12
0.12
0.04
0.04
0.08
Tissue
LIVER
THYROID
BONE SURFACE
BRAIN
KIDNEYS
SALIVARY GLANDS
SKIN
REMAINDER TISSUES
2007 wT
0.04
0.04
0.01
0.01
0.01
0.01
0.01
0.12*
* Adrenals, extrathoracic airways, gall bladder, heart wall, kidney, lymphatic nodes, muscle, pancreas,
oral mucosa, prostate, small intestine wall, spleen, thymus, uterus/cervix
25. HPA Working Party on Dental Cone Beam CT
Equipment (2010)
Guidance on the Safe Use of Dental Cone Beam CT
(Computed Tomography) Equipment. Health
Protection Agency
https://www.gov.uk/government/uploads/system/
24. Svenson B, Sjoholm B, Jonsson, B (2004)
uploads/attachment_data/file/340159/HPARadiation of absorbed doses to the thyroid
CRCE-010_for_website.pdf
gland in orthodontic treatment planning by
26. European Commission (2012)
reducing the area of irradiation
Cone beam CT for dental and maxillofacial radiology
Swedish Dental Journal 28, 137-47
(Evidence-based guidelines). Radiation Protection
no 172. Luxembourg: Publications Office
http://www.sedentexct.eu/files/radiation_
protection_172.pdf
23. ICRP (2007)
The 2007 Recommendations of the
International Commission on Radiological
Protection. ICRP Publication 103
Annals of the ICRP, 37, 2-4
6
Figure 1. Use of a
thyroid shield
when taking an
upper occlusal
EFFECTIVE DOSES AND RISKS FROM
EXPOSURE TO X-RAYS IN ORTHODONTIC PRACTICE
Two publications, one from the Health Protection Agency 25
and the other from the European SEDENTEXCT consortium,26
on radiation dose have been used to produce the comparative
figures of effective dose (E) from common orthodontic
radiographic examinations and other medical examinations
(Table 2). Further details regarding effective doses from
different CBCT examinations are given in Section 11.
ORTHODONTIC RADIOGRAPHS
Effective dose (mSv)
X-RAY EXAMINATION
INTRA-ORAL PERIAPICAL/BITEWING
PANORAMIC
UPPER STANDARD OCCLUSAL
LATERAL CEPHALOMETRIC
CHEST
BARIUM SWALLOW
BARIUM ENEMA
CT MANDIBLE AND MAXILLA
DENTO-ALVEOLAR (small volume) CBCT
CRANIOFACIAL (large volume) CBCT
0.0003 – 0.022
0.0027 – 0.038
0.008
0.0022 – 0.0056
0.014 – 0.038
1.5
2.2
0.25 – 1.4
0.01 – 0.67
0.03 – 1.1
ESTIMATED RISKS
Orthodontic patients are generally examined using low dose
radiographic examinations and are primarily at risk from the
stochastic effect of cancer induction. ICRP currently estimate
that there is a 1 in 20,000 chance of developing a fatal cancer
for every 1 mSv of effective dose of radiation. Using this figure,
an estimate of risk from various X-ray examinations can be
calculated and is shown in Table 3.
TABLE 3: Risks of cancer from diagnostic X-rays
Estimated risk of fatal cancer
X-RAY EXAMINATION
INTRA-ORAL PERIAPICAL/BITEWING
USING 70KV, RECTANGULAR COLLIMATION,
F SPEED FILM/DIGITAL RECEPTORS
PANORAMIC
UPPER STANDARD OCCLUSAL
LATERAL CEPHALOMETRIC
CHEST
BARIUM SWALLOW
BARIUM ENEMA
1 in 10,000,000
1 in 1,000,000
1 in 2,500,000
1 in 5,000,000
1 in 1,000,000
1 in 13,300
1 in 9,100
Range of risk
COMPUTED TOMOGRAPHY
CT MANDIBLE AND MAXILLA
DENTO-ALVEOLAR (small volume) CBCT
CRANIOFACIAL (large volume) CBCT
1 in 80,000 to 1 in 14,300
1 in 2,000,000
to 1 in 30,000
1 in 670,000
to 1 in 18,200
Risk is age dependent, being highest for the young (most
orthodontic patients) and lowest for the elderly. The estimated
risks shown in Table 3 are based on a 30 year old adult. The
2004 European Guidelines on Radiation Protection in Dental
Radiology 27 recommended that these should be modified by the
multiplication factors shown in Table 4, which represents
averages for both males and females.
27. European Commission (2004)
European Guidelines on Radiation
Protection in Dental Radiology.
Radiation Protection 136.
Luxembourg: Publications Office
https://ec.europa.eu/energy/sites/ener/
files/documents/136.pdf
TABLE 4: Age risk relationship
AGE GROUP (year)
Multiplication factor for risk
< 10
10 – 20
20 – 30
30 – 50
50 – 80
80 +
x3
x2
x 1.5
x 0.5
x 0.3
Negligible
Young orthodontic patients are particularly at risk and especially
when potentially high dose CBCT examinations are undertaken.
Figures for dose and risk such as those detailed above are
derived from laboratory studies using controlled conditions and
specific types and combinations of equipment. The ‘real world’,
in contrast, is full of variables and it is important to recognise
that doses delivered may vary significantly depending upon the
X-ray equipment used (Figure 2).28, 29
Acceptable
Reference
Dose
Unacceptable
20
N U M B E R O F X- R AY SE TS
TABLE 2: Frequency and collective dose for medical and dental X-ray examinations in the UK
15
10
5
20
30
40
50
60
70
80
90
100
DAP (mGy cm2)
Figure 2. Surveys of panoramic X-ray
units show a wide variation in dose for
exposures in children. The National
Reference ‘Dose-Area-Product’ level for
this examination is 67mGy/cm2.
Exposures in excess of this value result in
some children receiving a higher
radiation dose than is needed to achieve
an image of adequate quality 28
© Crown copyright. Adapted from
the original, with permission of
Public Health England
28. Hart D, Hillier MC, Shrimpton PC (2010)
Doses to Patients from Radiographic and
Fluoroscopic X-ray Imaging procedures in
the UK - 2010 review. HPA-CRCE-034.
Health Protection Agency
29. Lecomber AR, Downes SL, Mokhtari M,
Faulkner K (2000)
Optimisation of patient doses in
programmable dental panoramic radiography
Dentomaxillary Radiology 29, 107-12
7
8
IMAGING EQUIPMENT AND
TECHNIQUES AVAILABLE FOR
ORTHODONTIC RADIOGRAPHY
X-RAY GENERATING EQUIPMENT
PANORAMIC UNITS
From a radiation protection point of view, X-ray generating
equipment cannot be considered ‘safe’, unless it is in good order
both electrically and mechanically and delivers a dose at or below
the recommended diagnostic reference levels (DRLs). To try to
ensure that equipment is ‘safe’, all units must be subjected to
the following tests:
• Equipment should have a range of tube potential settings,
• ‘Critical examination’ test by the installer
• ‘Acceptance’ test by a medical physicist or radiation protection
adviser (RPA) before the equipment is used clinically
preferably from 60 to 90 kV
• Beam height should not be greater than the image receptor
in use (normally 125 mm or 150 mm)
• Equipment needs to be provided with patient positioning
aids, incorporating light beam markers (Figure 4)
• New equipment should provide facilities for field-limitation
techniques.
• ‘Routine’ tests by a medical physicist or radiation protection
adviser (RPA) after appropriate intervals (3 years) and after
any major maintenance procedure
• Dose measurements to assess patient doses – usually part
of the ‘acceptance test’.
The legislation requires an equipment log to be maintained,
containing details of the equipment’s installation and
maintenance record. In addition the 2001 Guidance Notes make
specific recommendations for different types of X-ray equipment: 30
DENTAL X-RAY EQUIPMENT
•
•
The operating range should be in the range of 60-70 kV
The equipment should operate within 10% of the stated
or selected kV
•
Equipment operating at less than 70 kV should include
1.5mm of aluminium filtration, and 2.5 mm if operating
over 70 kV
•
Beam diameter should not exceed 60 mm at the patient
end of the spacer cone or beam indicating device but ideally
should include rectangular collimation (40 mm x 50 mm)
Figure 4.
Light beam
markers to aid in
patient positioning
CEPHALOMETRIC EQUIPMENT
•
Equipment should have film speed controls and finely
adjustable kV, mA and exposure times
• The equipment must be able to ensure the precise
•
Equipment should ideally have DC or constant
potential output
• The focus to film distance should be in the range of
•
Focal spot position should be marked on the
tubehead casing
• Should be triangular collimated to avoid unnecessary
•
The focus-to-skin distance (fsd) should be
200 mm (Figure 3).
alignment of the X-ray beam, image receptor and the patient
1.5 –1.8 m to minimise magnification effects
exposure of the cranium.
ALL EQUIPMENT
• There should be a light on the control panel to show
that the power supply is on
• Audible and visible warning signals during an exposure
should be fitted
• Exposure switches (timers) should only function
while continuous pressure is maintained on the switch
and terminate if pressure is released
• Exposure switches should be positioned so that the operator
can remain outside the controlled area and at least two
metres from the X-ray tubehead and patient
Figure 3.
X-ray tubehead
showing focus to skin
distance (fsd)
8
• Exposure times should be terminated automatically.
30. Department of Health (2001)
Guidance Notes for Dental Practitioners on the
Safe Use of X-ray Equipment
https://www.gov.uk/government/publications/
dental-practitioners-safe-use-of-x-ray-equipment
ORTHODONTIC RADIOGRAPHS
IMAGE RECEPTORS – FILM AND DIGITAL
CONE BEAM COMPUTED TOMOGRAPHY (CBCT)
Modern image receptors available include:
Low dose cone beam CT technology has been developed
specifically for use in the dental and maxillofacial regions.
The concept of a three dimensional radiograph may seem
attractive as the imaging modality of choice. Whilst it has many
applications on oral surgery, implantology and periodontology,
its use in orthodontics is limited. This is discussed fully in
Section 11.
Radiographic film
• Direct action film, also referred to as packet film (intra-oral)
• Indirect action film used in conjunction with rare-earth
intensifying screens in a cassette (extra-oral).
Digital receptors
• Solid-state sensors
These consist of a scintillator that converts X-radiation to light,
mounted on a photodetector, and associated electronics encased
in a small, thin, flat, rigid, plastic rectangular housing.
Underlying technology involves either amorphous silicon-based
charge-coupled devices (CCD) or complementary metal oxide
semiconductors (CMOS). Suitable size sensors are available for
periapical/bitewing, panoramic and skull radiography. Occlusal
sized sensors are not available. After exposure the image
appears immediately on the computer monitor.
• Photostimulable phosphor plates
These typically consist of a layer of barium fluorohalide phosphor
on a flexible plastic backing support. Suitable sized phosphor
plates are available for all dental radiographic techniques.
After exposure the plates are read by a laser scanning device,
following which the image appears on the computer monitor.
Equipment and theory
CBCT technology, for use in the dental and maxillofacial
regions, was developed in the late 1990s. Its development
has proliferated over recent years. It shares some technological
characteristics with conventional CT, but is not identical to it.
CBCT is probably best described as ‘volumetric imaging’ as the
technique uses X-rays in a different way to conventional radiography: to image different sized spherical or cylindrical volumes,
described as small, medium or large fields of view (FOV).
Several machines are currently available with new developments
constantly being launched. Designs vary but essentially resemble
panoramic units (Figure 5). The equipment employs a coneshaped X-ray beam (rather than the flat fan-shaped beam used
in conventional CT) and a special detector – typically a flat panel
(either amorphous silicon or CMOS) or an image intensifier
which captures the attenuated X-ray beam. The X-ray tube has
a potential which may be fixed or variable within a range
of 60 kV to 120 kV.
Figure 5.
Patient positioning
for CBCT showing
light markers, head
restraint and
thyroid collar
9
ORTHODONTIC RADIOGRAPHS
Image Creation
The scanning/image creation process divides into three stages:
(Figure 6)
Stage 1 – Data acquisition. The patient is positioned within
the unit and their head secured. The equipment orbits around
the patient, taking approximately 10 – 40 seconds, and in one
scan, images the cylindrical or spherical field of view (FOV). As
all the information is obtained in the single scan, the patient
must remain absolutely stationary throughout the exposure. The
size of the cylindrical or spherical field of view varies from one
machine to another. Using a medium-sized field of view (typically
15 cm diameter) most of the maxillofacial skeleton fits within the
cylindrical or spherical shape. The hard tissues, teeth and bones,
are imaged well, but little detail is provided on the soft tissues.
Stage 2 – Primary reconstruction. The information from the
entire scan is collated by computer which then divides the
volume into tiny isotropic cubes or voxels (ranging in size from
0.076 mm3 and 0.4 mm3) and calculates the X-ray absorption
in each voxel. As with pixels in two dimensional digital imaging,
each voxel is then allocated a shade from the grey scale from
black through to white. Typically one scan contains over
100 million voxels.
Stage 3 – Secondary or multiplanar reconstruction.
The computer software displays a set of images in the axial,
sagittal and coronal planes on the monitor which can then be
scrolled through in real time (Figure 7). Selecting and moving
the cursor on one image, automatically allows the image in the
Stage 1
selected plane to be scrolled through simultaneously. Multiplanar
reconstruction also allows the creation of linear or curved
cross-sections within the volumetric dataset, for clinical use.
For example, this enables the creation of panoramic images
made up of the voxels that coincide with the plotted arch shape.
In addition it is also possible to reconstruct or synthesise lateral
cephalometric images and with appropriate software to produce
so-called volume rendered or surface rendered images.
DIGITAL IMAGE STORAGE
Digital images need to be securely saved and backed up to
an appropriate computer/server. In most hospitals this storage
is accomplished using a Picture Archiving & Communication
System (PACS). PACS allows the storing, transmission and
viewing of digital images at sites remote from the
site of production.
Stated benefits of PACS
• Images cannot be lost or destroyed
• Images are always available
• Fast transfer to remote locations via an
appropriate network
• The identical image can be viewed at the same
time in different locations which may be of
benefit when seeking opinions.
These stated benefits rely on efficient IT facilities
and interactions (software and hardware).
Stage 2
Stage 3
SAGITTAL
AXIAL
Figure 6. Diagram showing the basic 3-stage concept of
a large field of view (FOV) CBCT scan
Stage 1 – Data acquisition – a cone shaped X-ray beam orbits once around the patient
obtaining data of a cylindrical volume
CORONAL
Stage 2 – Primary reconstruction – the computer divides the cylindrical volume into tiny cubes or voxels
Stage 3 – Secondary or multiplanar reconstruction – the computer creates separate images in the sagittal, coronal
and axial anatomical planes (From Whaites E and Drage N, Essentials of Dental Radiography and Radiology
5th Edition (2013), Elsevier/Churchill Livingstone)
AXIAL
10
SAGITTAL
Figure 7. Small FOV CBCT images of an unerupted right canine. The sagittal section shows resorption of the lateral incisor
CORONAL
ORTHODONTIC RADIOGRAPHS
9
METHODS OF RADIATION
PROTECTION INCLUDING
QUALITY ASSURANCE
THE various practical and physical methods available for
reducing or limiting the dose to patients, and thereby limiting
the risk, from orthodontic radiography can be summarised
into four categories:
• Equipment
• Staff training
• Radiographic techniques used
• Clinical judgement on the need/justification and ability to
interpret, therefore maximising the diagnostic information
contained within, the image.
the Safe Use of X-ray Equipment 32 specified the content of
update courses. The General Dental Council (GDC) currently
highly recommends ‘Radiography and Radiation Protection’
as one of their verifiable Continuing Professional Development
(CPD) subjects, suggesting five hours within a five
yearly CPD cycle.
Employers are required to keep a register of staff and their
training, as part of their overall quality assurance programme,
including the following information:
Together, these first three factors determine the quality of the
images produced and should be subject to a quality assurance
(QA) programme.
• Name
• Responsibility (IRMER Referrer, Practitioner or Operator)
• Date and form of training received
• Recommended date for a review of training needs.
EQUIPMENT
RADIOGRAPHIC TECHNIQUES USED
X-ray generating equipment should:
Intra-oral periapicals and bitewings should:
• Operate at high voltage (60 – 70 kV for intra-oral equipment)
• Incorporate adequate aluminium filtration
• Incorporate appropriate beam collimation
• Be both critically examined and acceptance tested
• Include modern exposure controls allowing very short
• Involve the use of image receptor holders and beam
•
aiming devices
exposure times
• Be taken using rectangular collimation
• Ensure accurate positioning to avoid retakes
• Involve the minimum number of images
• Be digitally or chemically processed correctly.
Incorporate warning signals.
(Figures 8a & 8b)
Digital image receptors should:
• Be used with exposures that have been optimised in
consultation with the Radiation Protection Advisor (RPA).
Note: Different types of receptors require different
exposure settings.
Film based image receptors should:
• Be the fastest available film speed – typically F speed
• Involve rare-earth intensifying screens for extra-oral
radiography.
A
STAFF TRAINING
B
IRMER Practitioners and IRMER Operators should:
• Be adequately trained. The British Society of Dental and
Maxillofacial Radiology has defined adequate training in its
latest core curricula in dental radiography and radiology for
different members of the dental team.31 It is the responsibility
of the employer to ensure that all staff who are involved in
medical exposures have received adequate and appropriate
training in the field of radiation protection
• Regularly update their knowledge. The legislation not only
Figures 8a & 8b.
Patient positioning:
(a) Paralleling
technique periapical
(b) Bitewing
requires adequate training initially but also requires IRMER
practitioners and IRMER operators (including DCPs) to
regularly update their knowledge and skills. The Department
of Health’s 2001 Guidance Notes for Dental Practitioners on
31. British Society of Dental and Maxillofacial
Radiology (2015)
Core Curricula in Dental Radiography and
Radiology for the Dental Team
www.bsdmfr.org.uk
32. Department of Health (2001)
Guidance Notes for Dental Practitioners on the
Safe Use of X-ray Equipment. London, the
Stationery Office
https://www.gov.uk/government/publications/
dentalpractitioners-safe-use-of-x-ray-equipment
11
ORTHODONTIC RADIOGRAPHS
Intra-oral occlusal radiographs should:
• Be taken using rectangular collimation
• Include the use of a thyroid shield or collar if the
thyroid gland lies in the primary beam (not indicated
for a lower occlusal) (Figure 9).
Figure 11. Panoramic
radiograph showing the area
marked in yellow that would
result if field limitation 'dentition
only' techniques were used
True lateral cephalometric skull radiographs should:
• Ensure accurate patient positioning assisted by light
beam markers
Figure 9.
Patient
positioning
upper occlusal
Panoramic radiographs should:
• Ensure accurate patient positioning assisted by
light beam markers (Figure 10)
• Allow field limitation techniques and appropriate
collimation of panoramic images such as dentition
only, which results in a 50% dose reduction (Figure 11).
• Include triangular collimation, facilitated by a light
beam diaphragm, so as not to irradiate the whole of
the cranium and neck
• Include an aluminium wedge filter, ideally at the X-ray
tubehead, to facilitate the imaging of the soft tissues.
Note: There are three main designs of modern digital combined
panoramic/cephalometric units available that utilise different
techniques to produce lateral cephalometric images:
One shot – using a phosphor plate or a solid state receptor
Horizontal scanning – using solid state receptor (Figure 12)
Vertical scanning – using a solid state receptor
At present these units do not enable triangular collimation
nor incorporate aluminium wedge filters.
Cone beam imaging should:
• Ensure accurate patient head position using light beam markers
• Keep patient’s head stationary by use of suitable head restraints
• Allow FOV size to be adjusted – small, medium or large – as
required to select the smallest field of view compatible with the
clinical situation
• Allow resolution protocols/settings to be selected consistent
with diagnostic needs
• Allow kV and mAs to be varied to optimise image quality and
minimise radiation dose
• Use a thyroid shield if available, and certainly for larger
fields of view (Figure 5, page 9).
12
Figure 10.
Patient
positioning
panoramic
ORTHODONTIC RADIOGRAPHS
Figure 12.
Patient positioning.
Lateral cephalometric
radiograph in
horizontal scanning
direct digital unit
QUALITY ASSURANCE (QA)
The World Health Organisation has defined radiographic quality
assurance programmes as:
‘…an organised effort by the staff operating a facility to ensure
that the diagnostic images produced by the facility are of
sufficiently high quality so that they consistently provide
adequate diagnostic information of the lowest possible cost and
with the least possible exposure of the patient to radiation’.33
Terminology
• Quality control
The specific measures for ensuring and
verifying the quality of the radiographs produced
• Quality assurance
The arrangements to ensure that the
quality control procedures are effective and that they lead
to relevant change and improvement
• Quality audit
The process of external reassurance and
assessment that quality control and quality assurance
mechanisms are satisfactory and that they work effectively.
QA in dental radiography should ensure that optimum
diagnostic information can be obtained from radiographs while
radiation doses to patients and staff are kept as low as is
reasonably practicable (ALARP). While this should be principally
a matter of professional ethics, much of the ethical responsibility
has been complemented by the need to operate in accordance
with relevant statutory requirements in which many of the
necessary operational objectives are specified. Both the IRR 99
and IRMER contain elements relating to QA.
All dental practitioners are required to maintain a QA
programme, which must include standards of both equipment
and techniques together with quality control procedures to
assure that these standards are achieved and maintained.
Full details of Quality Assurance are provided for film-based
imaging in the 2001 Guidance Notes.34
A well-designed QA programme should not only be
comprehensive, but also inexpensive to operate and maintain.
Standards should be well-defined and require infrequent
modification. The maintenance of the necessary records will
necessitate a systematic and methodical approach.
REPORTING
In the context of reporting conventional radiographs, it is
reasonable to assume that the possession of a registered dental
qualification, supplemented by relevant CPD during the course
of a career, is evidence of adequate training to comply
with IRMER.
The following are the clinician’s legal requirement:
• To examine the requested radiographs
• To evaluate the findings
• To record the findings in the patient’s clinical notes.
CLINICAL JUDGEMENT
The use of selection criteria together with clinical judgement
should ensure that the appropriate information is gained at
minimal risk to the patient. This is considered in the
next section.
33. World Health Organization (1982)
Quality Assurance in Diagnostic Radiology.
Macmillan/Procrom, Geneva
http://whqlibdoc.who.int/
publications/1982/9241541644.pdf
34. Department of Health (2001)
Guidance Notes for Dental Practitioners on the
Safe Use of X-ray Equipment (Chapter 5).
London, the Stationery Office
https://www.gov.uk/government/publications/
dentalpractitioners-safe-use-of-x-ray-equipment
13
10
SELECTION CRITERIA FOR THE
USE OF RADIOGRAPHS IN
ORTHODONTICS
IT MUST be remembered that the prescription of a radiograph
Figure 13.
An unerupted
canine could not
be palpated.
A periapical
radiograph shows
the canine to be
present and
resorption of the
lateral incisor root
is a procedure with a low, but nevertheless inferred, risk and
therefore each radiograph must be clinically justified as required
by IRMER.35 This will involve an assessment as to whether the
information can be gained by less invasive means (such as,
study casts or clinical examination).
Additional information may be required from radiographs
when a clinical examination suggests the presence of an
abnormality, or when interceptive and active orthodontic
treatment is being considered.
Such as:
• The presence or absence of permanent teeth
• The presence and position of misplaced or
supernumerary teeth
• The stage of development of permanent teeth
• The morphology of unerupted, and sometimes erupted, teeth
• The presence and extent of dental disease
• The presence, extent, and type of any developmental
anomalies.
For treatment planning it is frequently necessary to be able to
assess accurately the relationships of the teeth to the jaws, and
the jaws to the rest of the facial skeleton.
In addition, radiographs may be used in the presence of clinical
indicators to assess treatment progress and growth changes.
Where appropriate they may be used in teaching and research.
INTRA-ORAL RADIOGRAPHS
Periapical views
These can be taken to determine the presence and position
of unerupted teeth, the presence or absence of apical disease
or root form (Figure 13).
A
Figures 14a & 14b.
a) The deciduous canines
are retained and the
unerupted canines could
not be palpated buccally.
The panoramic image
shows that the maxillary
canines are misplaced.
The lower right
second premolar is
developmentally absent
When canines are ectopically positioned, periapical views can
form part of a parallax technique and, in certain cases, allow
assessment of resorption of lateral incisor roots. Other periapical
views may also be indicated when a clinical examination, a
panoramic radiograph, or a treatment history, necessitates
further investigation.
Full mouth periapical views are rarely indicated as dental
panoramic radiographs offer a similar amount of information
with a much-reduced exposure.36
b) Standard occlusal
radiograph of the same
patient demonstrates
misplaced maxillary
canines. Using vertical
parallax, in conjunction
with the panoramic image
above, the canines
are shown to be
palatally placed
Upper standard occlusal radiograph
This image shows the maxillary incisor region and may be taken
when there is a clinical indication of potential underlying disease
or developmental anomaly in this area.
B
An occlusal image is helpful in assessing the position of
misplaced and unerupted canines. With the parallax technique
used in conjunction with a periapical image or a panoramic
radiograph the bucco-palatal position of unerupted teeth
can be determined (Figures 14a & 14b).
14
36. Brucks A, Enberg K, Nordqvist I, Hansson
35. Health and Safety Legislation (2000)
AS, Jansson L and Svenson B (1999)
The Ionising Radiation (Medical Exposure)
Radiographic examinations as an aid to
Regulations 2000. SI 2000 No 1059. London,
orthodontic diagnosis and treatment planning
the Stationery Office (IRMER)
Swedish Dental Journal 23, 77-85
http://www.legislation.hmso.gov.uk/si/
si2000/20001059.htm
ORTHODONTIC RADIOGRAPHS
EXTRA-ORAL RADIOGRAPHS
Dental panoramic radiographs
The principal use of panoramic radiographs for orthodontic
patients is to confirm the presence, position and morphology
of unerupted teeth (Figure 15a).
Only gross caries will be detected with acceptable accuracy on
panoramic radiographs. Caries diagnosis requires clinical
examination supplemented by selected special tests, including
bitewing radiography.
One limitation of panoramic radiographs is that the focal trough
is relatively narrow particularly in the incisor region. If a tooth is
inclined or malpositioned, the crown, root and apex may not all
lie within the focal trough. As a result, parts or all of the tooth
may appear out of focus or even invisible.
A
Figures 15a and 15b.
a) The permanent
canines could not
be palpated. The
panoramic image
shows a full
complement of
permanent teeth.
The lower left
deciduous canine is
retained. The lower
left canine is severely
misplaced
Indications for dental panoramic radiographs
The Faculty of General Dental Practice (UK) in their 2013
Selection Criteria for Dental Radiography 38 booklet specified
criteria for the use of panoramic radiographs in general dental
practice, of which the most relevant to orthodontics is:
• ‘A panoramic radiograph is commonly used to provide
information on the state of the dentition and is often
appropriate when orthodontic treatment is being considered’.
b) The lateral
cephalometric
radiograph of the
same patient shows
the lower left canine
labial to the lower
incisors
In addition the following warning is given:
• ‘Routine screening of children cannot be justified’.
B
Additional indications are:
• To obtain views of the incisor region when detailed
information is required concerning the incisor apical region
• Occasionally to supplement a panoramic radiograph when a
possible abnormality is suspected on examination of the
panoramic image.
Bitewings
• Where teeth have a questionable prognosis bitewing
radiographs may be necessary, although communication
with the clinician who placed the restoration, and who may
have a recent radiograph, will often avoid the need for an
additional image
• Bitewings may be indicated to check the caries status of a high
risk patient who is to undergo fixed appliance treatment.37
These criteria rule out the practice of taking panoramic
radiographs for all new patients, and for using this type of
imaging to ‘screen’ asymptomatic patients. They also
explain that panoramic radiography is not appropriate for
investigation of most patients presenting with symptoms of
temporomandibular joint disorders (see Section 13).
The flow charts (Figures 17 & 18) give guidance for the
use of orthodontic radiographs.
LATERAL CEPHALOMETRIC RADIOGRAPHS
Cephalometric images may be used to aid diagnosis and
treatment planning and when appropriate provide a baseline
for monitoring progress (Figures 15b & 16). The images must be
analysed to obtain the maximum clinical information. In
malocclusions where the incisor relationship does not require
significant change such radiographs are unlikely to be required.36
Patients who may require lateral cephalometry include those
with a skeletal discrepancy when functional appliances or fixed
appliances are to be used for labio-lingual movement of
the incisors.
In addition, cephalometric radiographs can be of assistance in
the location and assessment of unerupted, malformed, or
misplaced teeth and to give an indication of upper incisor root
length. There is no evidence that a single lateral cephalometric
radiograph is of use in the prediction of facial growth and
images should not be taken for this purpose.39
37. European Commission (2004)
European Guidelines on Radiation Protection in
Dental Radiology. Radiation Protection 136.
Luxembourg: Publications Office
https://ec.europa.eu/energy/sites/ener/files/
documents/136.pdf
38. Horner K, Eaton K (eds) (2013)
Selection Criteria for Dental Radiography
(3rd edition). Faculty of General Dental
Practice (UK)
39. Houston WJB (1979)
The current status of facial growth
predictions: a review
British Journal of Orthodontics 6, 11-17
15
ORTHODONTIC RADIOGRAPHS
ASSESSMENT AND TREATMENT PLANNING
The clinical examination of a patient forms the most important
part of assessment and treatment planning, to which
radiographs are complementary. This has been demonstrated
in a number of research projects.
Figure 16. A patient
with a Class II
malocclusion on a
marked skeletal 2 base
who will require
complex treatment –
a clear indication for a
lateral cephalometric
radiograph
Indications for lateral cephalometric radiography
The flow charts (Figures 19 & 20) give an indication as to
when lateral cephalometric images may be required. If clinicians
choose to take lateral cephalometric radiographs for other
reasons than those suggested, they must have clinical reasons
to justify their decision.
Cone beam CT
Because of recent advances the use of CBCT is considered
separately and in detail in Section 11.
OTHER VIEWS
Over the years, a number of other views have been advocated
but have not gained wide acceptance. Postero-anterior views of
the skull may be of use in those patients who present with facial
asymmetry, and may occasionally be helpful in the assessment
of certain jaw or dental anomalies. The vertex occlusal view has
few, if any, indications and is no longer recommended and is
only of historical interest.40
The use of hand wrist radiographs to predict growth spurts has
been shown not to be sufficiently accurate to be of value.41, 42
It has been suggested that the skeletal maturation of a patient
can be assessed from the stages of calcification of the cervical
vertebrae using the method reported by Bacetti,43 provided the
lateral skull has not been collimated and the vertebrae are
included in the image. However, both this approach and that of
the use of hand wrist radiographs appear to have limited clinical
application.44
WHEN ARE ORTHODONTIC RADIOGRAPHS INDICATED?
Following a clinical examination and before requesting
radiographs the following questions should be asked: 45
Do I need it?





16
Does the management of the patient’s
condition depend upon a radiograph?
Do I need it now?
Is it likely that the condition will
resolve or progress?
Has it been done
already?
Repeat radiographs deliver additional
radiation dose. The introduction of digital
transfer of data may reduce this.
Is the correct radiograph being requested?
Is a radiograph essential for diagnosis and justified?
Have I made a clinical assessment?
To make an assumption that a radiograph is necessary to
complete a diagnosis and request a radiograph before a clinical
examination, in order to facilitate patient flow through a clinic or
practice, is unlawful.
One such study found that 74% of radiographs taken for
orthodontic purposes did not alter the initial diagnosis or
treatment plan.46 The same group of authors later found that the
use of algorithms reduced the need for radiographs by 36%.47
Other work has shown that radiographic findings altered
treatment planning decisions in fewer than 10% of cases.48, 49
Deciduous dentition
There are few non-syndromic conditions that require
radiographs in the deciduous dentition.
Mixed dentition
A high proportion of orthodontic patients will be referred in
the mixed dentition.
If, following the clinical examination, active orthodontic
treatment or interceptive extractions are not thought necessary
radiographs to check the presence or otherwise of developing
successional teeth are not indicated.
There may be patients who require early treatment, often with
removable appliances, where extractions are not indicated.
In such cases, in the absence of specific factors, treatment
may be carried out without the need for radiographs.
When a clinical examination clearly suggests the need to extract
deciduous or permanent teeth it is essential to ascertain the
presence and position of unerupted permanent successors with
the use of appropriate radiographs.
In patients who require functional appliances it is often
appropriate to obtain cephalometric images at the
commencement of treatment in order to monitor the changes
that may be taking place during treatment.
Adolescent dentition
In older patients where all successional teeth including the
second molars have erupted, radiographs may not be necessary.
Radiographs are not essential prior to carrying out orthodontic
tooth movement unless there are clinical indicators. They may
be required to assess the presence or absence of third molars
where that may influence extraction choice. In these situations
field limitation (dentition only) techniques should be used.
Where the incisor relationship will remain relatively unaltered
during treatment cephalometric radiographs are unlikely to
be required.
When a significant alteration in the incisor relationship is
planned or functional appliances are to be used a lateral
cephalometric radiograph may be indicated.
43. Baccetti T, Franchi L,
40. Jacob SG (2000)
46. Atchinson KA, Luke LS,
McNamarra J (2002)
White SC (1992)
Radiographic localization of
An improved version of the
An algorithm for ordering
unerupted teeth: Further
Cervical Vertebral Maturation
pre-treatment orthodontic
findings about the vertical
(CVM) method for the assessment
radiographs
tube shift method and other
of mandibular growth
localization techniques
American Journal of
Orthodontics and Dentofacial
Angle Orthodontist 72, 316-25
American Journal Orthodontics
Orthopedics 102, 29-44
and Dentofacial Orthopedics
44. Mellion ZJ, Behrents RG,
118, 439-47
47. Brucks A, Enberg K,
Johnston LE Jr (2013)
Nordqvist I, Hansson A S,
41. Houston WJB, Miller JC,
The pattern of facial skeletal
Jansson L, Svenson B (1999)
Tanner JM (1979)
growth and its relationship to
Radiographic examinations as
Prediction of the timing of the
various common indexes of
an aid to orthodontic diagnosis
adolescent growth spurt from
maturation
and treatment planning
ossification events in
American Journal of Othodontics
hand-wrist films
Swedish Dental Journal 23,
and Dentofacial Orthopedics,
77-85
143, 845-854
British Journal of Orthodontics
6, 145-52
48. Atchinson KA, Luke LS,
45. Irish Institute of Radiography
White SC (1991)
42. Flores-Mir C, Nebbe B,
Best practice guidelines
Major PW (2004)
Contribution of pre-treatment
http://www.iirrt.ie/about-us/bestradiographs to orthodontists’
Use of skeletal maturation based
practice-guidelines
decision making
on hand-wrist radiographic
analysis as a predictor of facial
Oral Surgery Oral Medicine
Oral Pathology 71, 238-45
growth: a systematic review
Angle Orthodontist 74, 118-24
ORTHODONTIC RADIOGRAPHS
Where waiting lists are in operation and treatment may be
required it is advisable to delay the exposure of radiographs
until they can be shown to be necessary to influence the
treatment plan.
Adult dentition
In patients with a healthy dentition and supporting structures,
orthodontic treatment may be carried out without the need
for radiographs. History of previous orthodontic treatment
needs investigation, and localised intra-oral radiographs
may be required.
When a significant change in the incisor position is planned or
where the periodontal condition is in question, appropriate
radiographs may be required.
Where a combination of orthodontics and orthognathic surgery
is indicated the guidelines issued by the BOS/British Association
of Oral and Maxillofacial Surgeons (BAOMS) should be followed.50
MONITORING OF TREATMENT
Radiographic monitoring may be needed during treatment but it
is important to make a careful clinical assessment to ensure that
the patient will benefit from further imaging.
uncertain either as a result of a specific type of treatment or
because unfavourable growth is anticipated. Radiographs may
be required if there are clinically observed changes at the end of
retention in order to provide a baseline from which to assess
further movement. The need for such radiographs must be
clearly explained to the patient or parent and consent obtained.
Ideally every radiograph should be of benefit to the individual
patient, but the practice of orthodontics has benefited from the
analysis of post-treatment cephalometric views. If images are to
be taken after treatment, or after retention, for all patients this
must be part of a long-term research project. Such a project
must be designed to improve the clinician’s understanding of
malocclusion and therapeutics and the information gained is
used for the benefit of the population at large. Approval from
a local ethics committee is essential and informed consent
obtained from every patient participating. Approval for a
correctly structured research programme should not be
difficult to obtain (see Section 12).
The indications for differing radiographic projections are
summarised in Table 5.
TABLE 5: Choice of view for radiographic examination
Unerupted teeth
PROJECTION
FUNCTION
Monitoring the changes in the position of unerupted teeth may
only be satisfactorily achieved with radiographs.51
PANORAMIC
RADIOGRAPH
l
It is important to ensure that the repeat images are taken in a
position similar to the original to ensure a reliable comparison.
UPPER
STANDARD
OCCLUSAL
l
l
MANDIBULAR
OCCLUSAL
l
Localisation of unerupted teeth
PERIAPICALS
l
Assess root morphology
Assess root resorption
Assess apical disease
In combination with a standard occlusal or
second periapical to localise unerupted teeth
by parallax
Minor resorption of roots is common during orthodontic
treatment with fixed appliances.52, 53 However, there are cases
where resorption is appreciable. The indications for intra-oral
radiographs during treatment are:
• If there is evidence of excessive tooth mobility
during treatment
•
• Where treatment extends over a long period of time
• Loss of vitality
• In patients having a repeat course of treatment.
l
l
Iatrogenic factors
If there is evidence of excessive tooth mobility during treatment,
intra-oral radiographs may be necessary to provide an accurate
assessment of the underlying reason. Similarly, where there is
abnormal delay of tooth movement or an indication of apical
disease, intra-oral radiographs may be indicated.
l
l
l
BITEWINGS
l
l
l
LATERAL
CEPHALOMETRIC
RADIOGRAPH
l
CONE BEAM CT
l
l
Where there is abnormal delay in tooth movement
l
l
l
End of active tooth movement
In some cases the taking of a cephalometric image a month or
two before the completion of active treatment will enable the
clinician to check that treatment targets have been achieved and
allow planning of retention. The need to take radiographic
records when the active appliance is removed should be carefully
assessed for each patient and is unlikely to be indicated except
for patients with severe malocclusions.
Post treatment
The clinical justification for radiographs after treatment or at the
end of retention is difficult to define and has to be assessed for
each patient. They may be indicated in patients where stability is
Identification of the developing dentition
Confirmation of the presence/absence of teeth
Confirm the presence of unerupted teeth
Parallax localisation either with a panoramic
or periapical
To identify supernumerary teeth
Identification of developmental anomalies
Periapical or standard occlusal views may be needed to assess
changes in the position of unerupted teeth.
When a panoramic radiograph is requested to monitor the
changes in position of unerupted teeth, appropriate limitation of
the field size (dentition only) should be used.
l
l
Identification and assessment of severity of caries
Demonstration of periodontal bone levels
(complementing a thorough clinical examination)
Assessment of existing restorations
Assess skeletal pattern and labial segment angulation
Monitor the effects of treatment
In selected cases to localise impacted teeth with
particular reference to the postion of adjacent
teeth and posible resorption
To assess dental structural anomalies,
e.g., gemination, fusion, supernumeraries
In some cases of dental trauma where there is
suspected root fracture
For some complex cases of skeletal abnormality
Some cleft palate cases.
53. Roscoe MG, Meira JB,
49. Han U, Vig KWL, Weintraub JA, 51. Ericson S, Kurol J (1988)
Cattaneo PM (2015)
Vig PS, Kowalski CJ (1991)
Early treatment of palatally
Association of orthodontic force
Consistency of orthodontic
erupting maxillary canines by
system and root resorption:
treatment decisions relative to
extraction of the primary canines
A systematic review
diagnostic records
European Journal of Orthodontics
10, 283-95
American Journal of Orthodontics
American Journal of Orthodontics
and Dentofacial Orthopedics
and Dentofacial Orthopedics
52. Segal GR, Schiffman PH,
147, 610-26
100, 212-19
Tuncay OC (2004)
50. British Orthodontic Society
Meta analysis of the treatment(2005)
related factors of external apical
Orthognathic Minimum Data
root resorption
Set Advice Sheet 22. London:
Orthodontic Craniofacial Research
British Orthodontic Society
7, 71-8
17
X
Figure 17.
INDICATIONS FOR RADIOGRAPHS –
CHILD PATIENT LESS THAN 10 YEARS OF AGE
Have all
the incisors
erupted?
NO
YES
Are incisors
well aligned or
mildly crowded?
NO
YES
Is overjet
within normal
limits?
NO
YES
Have
first molars
erupted?
NO
YES
Review
18
Orthodontic Radiographs – Guidelines. © BOS
Is there a
clinical reason
to suspect an
abnormality?
Is there gross
crowding, marked
rotation or
displacement?
Is overjet
significantly
increased or
reversed?
Are
first molars
overdue?
YES
X-RAY
YES
Consider
YES
Consider
YES
X-RAY
X-RAY
X-RAY
X
Figure 18.
INDICATIONS FOR RADIOGRAPHS –
PATIENT OVER 10 YEARS OF AGE
Are incisors
well aligned or
mildly crowded?
NO
YES
Is overjet
or overbite within
normal limits?
NO
YES
Are deciduous
molars submerging
or retained past YES
normal age?
Is there
gross crowding,
displacement or
marked rotation?
YES
X-RAY
Class II
or
Class III?
YES
Consider
NO
X-RAY
YES
Review
X-RAY
X-RAY
NO
Have canines
erupted?
NO
YES
Are canines
palpable and in
a favourable
position?
YES
Are canines
in a normal
position?
YES
NO
Have
second molars
erupted?
NO
Consider
X-RAY
Is patient
over 14?
YES
Consider
X-RAY
NO
Review
19
Orthodontic Radiographs – Guidelines. © BOS
X
Figure 19.
IS A PRE-TREATMENT LATERAL CEPHALOMETRIC
RADIOGRAPH INDICATED IN A PATIENT AGED 10 –18?
Is the
overjet between
1mm and 5 mm?
YES
NO
YES
Is the
skeletal pattern
Class III?
YES
CEPH
NO
YES
YES
Is the patient
about to start
treatment?
NO
Review
YES
Not
indicated
YES
Is only the
upper arch
to be treated?
NO
Is occlusion
Class 2 div/ii or
bimaxillary
proclination
or compensated
Class III?
Are functional
appliances and/or
upper and lower
fixed appliances
to be used?
YES
Consider
CEPH
NO
Are upper and
lower fixed
appliances
planned?
YES
NO
Not
indicated
20
Orthodontic Radiographs – Guidelines. © BOS
Consider
CEPH
YES
Consider
CEPH
X
Figure 20.
IS A PRE-TREATMENT LATERAL CEPHALOMETRIC RADIOGRAPH
INDICATED IN A PATIENT OVER 18 YEARS OR BELOW 10 YEARS ?
YES
YES
Is the
patient over
18 years of age?
NO
YES
Is the patient
below 10 years
of age?
YES
Is the occlusion
a marked Class II
or Class III
which may need
early treatment or
monitoring?
YES
Consider
CEPH
NO
Review
Does the patient
want orthodontic
treatment or
orthognathic
surgery?
NO
Not
indicated
YES
Is the occlusion
a significant
Class II or Class III?
NO
YES
Is the occlusion
Class 2div/ii
or bimaxillary
proclination
or compensated
Class III?
NO
Not
indicated
YES
CEPH
CEPH
21
Orthodontic Radiographs – Guidelines. © BOS
11
APPLICATIONS OF CONE BEAM
COMPUTED TOMOGRAPHY (CBCT) IN
ORTHODONTICS
IN ORTHODONTICS, CBCT might be used for a variety of
reasons. Since the previous edition of these guidelines in 2008,
the literature has grown considerably. Establishing the diagnostic
efficacy of an imaging technique ideally requires evidence at
all levels, starting with technical efficacy (e.g., measurement
accuracy, reproduction of detail), diagnostic accuracy
(e.g., sensitivity, specificity), impact on treatment planning
decisions or patient outcomes and, at the highest level, the
cost-effectiveness at the societal level.
It is important to be aware that most knowledge on CBCT relates
to the lower levels of diagnostic efficacy. In the absence of
comprehensive evidence, this technique should be used
cautiously and in carefully selected situations. ‘Cephalometric
and panoramic radiographs appear to be sufficient in most
circumstances and should not be replaced with CBCT imaging.’ 54
USES OF SMALL FIELD OF VIEW (FOV) CBCT
Unerupted maxillary canines
The majority of CBCT examinations of young people are
undertaken for a localised examination of the anterior maxillary
region to assess the position of unerupted canine teeth and
suspected root resorption of incisors.55 There are now a number
of retrospective studies comparing orthodontists’ decisions
made on such clinical cases, with and without the availability of
CBCT imaging, which suggest that treatment plans are changed
in a minority of cases. The evidence suggests that clinicians’
confidence and consistency in treatment planning decisions
is improved.56, 57
There is improved accuracy of localisation of unerupted maxillary
canine teeth and identification of root resorption in incisor teeth
using a three-dimensional imaging technique. In most cases,
however, there is agreement between localisation and presence
of root resorption made using conventional radiographs and
CBCT imaging. 56, 58, 59, 60, 61
Previous UK and European guidelines 62 have suggested that
CBCT may be appropriate for the examination of unerupted
maxillary canines in selected cases where conventional
radiographs fail to provide adequate information. Such an
approach seems sensible. For example, conventional radiographs
may show root resorption of an incisor tooth with sufficient
detail to allow a treatment plan to be devised. CBCT could then
be reserved for equivocal cases or those with potential
complications.63, 64
TABLE 6: Ectopic canine selection criteria for localised CBCT examination
1. Take at least two conventional radiographs, permitting use of
parallax. This may be achieved using two intra-oral radiographs
or one intra-oral radiograph and a panoramic radiograph
2. Consider whether this is sufficient to make a treatment plan
3. If yes, no further imaging needed. If no, then consider localised CBCT.
54. Abdelkarim AA (2015)
Appropriate use of ionizing
radiation in orthodontic practice
and research
American Journal of Orthodontics
and Dentofacial Orthopedics
147, 166-8
22
55. Hidalgo-Rivas JA, Theodorakou
C, Carmichael F, Murray B,
Payne M, Horner K (2014)
Use of cone beam CT in children
and young people in three United
Kingdom dental hospitals
International Journal of Paediatric
Dentistry 24, 336-48
56. Alqerban A, Jacobs R,
57. Pittayapat P, Willems G,
Souza PC, Willems G
Alqerban A, Coucke W,
Ribeiro-Rotta RF, Souza PC,
(2009)
Westphalen FH, Jacobs R
In-vitro comparison of two
(2014)
cone-beam computer
Agreement between cone
tomography systems and
beam computed tomography
panoramic imaging for
images and panoramic
detected simulated canine
radiographs for initial
impaction-induced external
orthodontic evaluation
root resorption in maxillary
lateral incisors
Oral Surgery Oral Medicine
Oral Pathology Oral Radiology
American Journal of
117, 111-9
Orthodontics and Dentofacial
Orthopedics 136, 764.
e1-11; discussion 764-5
Other uses of small FOV CBCT
Other localised uses of small FOV CBCT can be considered, such
as assessment of unerupted dilacerated incisor teeth, as this
view can provide an accurate measurement of the angulation of
the dilaceration which might assist in treatment planning.
Surgical planning may also benefit from three-dimensional
information. An example is where unerupted teeth or
supernumerary teeth are to be surgically removed, but when
they are located in the region of important anatomical
structures. If the neurovascular structures cannot be shown to
be at a safe distance from the area of surgery on conventional
radiographs, then localised small FOV CBCT would be justified.
The use of CBCT for the assessment of cleft palate can be
justified where CT scans have been used in the past, as small/
medium FOV CBCT is likely to have a lower radiation dose.65 As
described in a recent review,66 CBCT can allow quantification of
the bone defect volume in the context of grafting, as well as
localisation of ectopic teeth which may be associated with clefts.
Cephalometric synthesis
The ability to produce a cephalometric image from a CBCT scan
is an attractive proposition. The images produced in this way are
described as synthesised cephalometric images. Many research
projects have compared conventional cephalometric images with
synthesised images. These have been carried out both on skulls
and also on patients. Much of the research has been related to
identifying the common cephalometric landmarks which can be
more accurately defined using CBCT.
To obtain a synthesised cephalometric image using CBCT
necessitates a large FOV scan which includes the sella turcica.
However, a small localised field of view is all that is usually
appropriate for most orthodontic treatment planning. When
such cases need cephalometric assessment then a separate
standard cephalometric image should be used.
The practice of taking a large volume FOV CBCT in order to
obtain cephalometric data is not indicated.54, 67
GENERALISED USES OF CBCT
The use of large FOV CBCT to image the entire dentition in
orthodontic assessment has been the subject of controversy.
Studies have shown that root angulation and position of teeth
is shown more accurately by CBCT than on panoramic
radiography.68, 69 There is, however, almost no evidence for
the impact of CBCT on diagnosis and treatment planning in
orthodontics apart from for the impacted maxillary canine.
Hodges et al (2013)70 studied cases where treatment plans
were made with conventional radiographs and study models
58. Haney E, Gansky SA, Lee JS,
Johnson E, Maki K, Miller AJ,
Huang JC (2010)
Comparative analysis of
traditional radiographs and
cone-beam computed
tomography volumetric images
in the diagnosis and treatment
planning of maxillary impacted
canines
American Journal of
Orthodontics and Dentofacial
Orthopedics 137, 590-7
61. Alqerban A, Jacobs R,
Fleuws S, Willems G (2015)
Radiographic predictors for
maxillary canine impaction.
American Journal of
Orthodontics and Dentofacial
Orthopedics 147, 345-54
64. Naoumova J, Kurol J,
Kjellberg H (2015)
Extraction of the deciduous
canine as an interceptive
treatment in children with palatal
displaced canines – part II:
possible predictors of success
and cut-off points for a
spontaneous eruption
European Journal of
Orthodontics 37, 219-29
62. HPA Working Party on Dental
Cone Beam CT Equipment
(2010)
Guidance on the Safe Use of
Dental Cone Beam CT
65. European Commission (2012)
(Computed Tomography)
Cone beam CT for dental and
59. Botticelli S, Verna C, Cattaneo
Equipment. Chilton: Health
maxillofacial radiology
PM, Heidmann J, Melsen B
Protection Agency
(Evidence-based guidelines).
(2011)
https://www.gov.uk/government/
Radiation Protection no 172.
Two-versus three-dimensional
uploads/system/uploads/
Luxembourg: Publications Office
imaging in subjects with
attachment_data/file/340159/
http://www.sedentexct.eu/files/
unerupted maxillary canines
HPA-CRCE-010_for_website.pdf
radiation_protection_172.pdf
European Journal of
63. Naoumova J, Kurol J,
66. Kapila SD, Nervina JM (2015)
Orthodontics 33, 344-9
Kjellberg H (2015)
CBCT in orthodontics: assessment
60. Wriedt S, Jaklin J, Al-Nawas B,
Extraction of the deciduous
of treatment outcomes and
Wehrbein H (2012)
canine as an interceptive
indications for its use
treatment in children with
Impacted upper canines:
Dentomaxillofacial Radiology
palatal displaced canines – part
examination and treatment
44, 20140282
I: shall we extract the deciduous
proposal based on 3D versus 2D
67.
Isaacson K (2013)
canine or not?
diagnosis
Cone beam CT and orthodontic
European Journal of
Journal of Orofacial Orthopedics
diagnosis
– a personal view
Orthodontics 37, 209-18
73, 28-40
Journal of Orthodontics 40, 3-4
ORTHODONTIC RADIOGRAPHS
and compared them with those made with CBCT. They
concluded that it contributed to treatment planning in cases
with an unerupted tooth, root resorption or a severe skeletal
discrepancy, but that CBCT should not be used routinely.
Large FOV CBCT allows the possibility of three-dimensional
measurements to be made. A recent systematic review found
limited evidence on efficacy of three-dimensional measurement
methods, of only moderate quality.71 Furthermore, there is no
standardised system of analysis. In the absence of any evidence
to show that three-dimensional measurements improve
treatment outcomes, they cannot be currently recommended.
radiation dose with CBCT, some of which are in the control of the
operator and some which are not. Those that are chosen by the
operator are shown in Table 8.
TABLE 8: Factors which can be used to reduce effective doses in CBCT
l Field of view dimensions
l Tube operating potential The combination of the lowest kV
(kV) and tube current
and lowest mAs settings consistent
exposure time product (mAs) with an adequate image quality
should be selected
l ‘Resolution’ settings
The lowest resolution consistent with
the diagnostic needs should be chosen
l Shielding
The use of thyroid shields containing
suitable X-ray absorbing material
should be considered
65
Recent European guidelines did not support the use of
large FOV CBCT as a routine part of orthodontic practice.
UK guidelines specifically condemned the practice if the
intention was solely to use the CBCT data to reconstruct
panoramic and synthesised cephalometric images.72
Radiation dose with CBCT
As with all radiographic imaging systems, the radiation dose
received by the patient is determined by many different factors.
It is not possible to give single dose value or to compare the
dose with numbers of periapical or panoramic radiographs.
Similarly, the same CBCT examination may result in a higher
effective dose in a child than in an adult, usually because the
thyroid gland is closer to the FOV. Many manufacturers of CBCT
equipment describe their product as ‘low dose’, a phrase that
should be read with considerable caution as the comparison is
often with conventional CT systems.
Data on effective doses from CBCT systems are available,65, 73
covering extremely wide ranges of effective dose for CBCT
examinations (Table 7). The more recent publication, a
meta-analysis, provides dose data for specific models of
CBCT equipment.73
TABLE 7: Effective doses for adult and child CBCT examinations
ADULTS
Field of view height (cm)
European Commission
(2012) 65
Ludlow et al (2015) 73
<10 cm
11- 674
(61*)
<10 cm
5- 652
(84+)
>10 cm
30 -1073
(87*)
10 -15 cm
9-560
(177+)
>15 cm
46 -1073
(212+)
CHILD
European Commission
(2012) 65
<10cm
16 -214
(43*)
>10cm
114 - 282
(186*)
Ludlow et al (2015) 73
<10cm
7- 521
(103+)
>10cm
13 - 769
(175+)
The values in this table are those reported in two systematic reviews, grouped by field of view height.
All effective dose figures are in microsieverts (μSv). Figures in parentheses are either *median or +mean values.
While higher effective dose levels are seen in children compared
with adults when the same equipment is used, fewer paediatric
studies have been performed, accounting for some higher values
for adults in these reviews.
It can be concluded that for most CBCT examinations, the
effective doses delivered are typically an order of magnitude
greater than those for conventional radiographic techniques.
Dose optimisation
If a decision to use CBCT has been made, then it is essential to
follow the principle of keeping all doses as low as reasonably
practicable (ALARP). There are many factors which influence
Use the smallest FOV consistent
with the diagnostic needs
While a few CBCT machines have a single fixed FOV, most new
machines will offer a choice.74 There is a correlation between the
size of the FOV and the effective dose, so this is a straightforward means of optimisation.65 As well as its radiation
protection advantages, a smaller FOV will require a shorter time
to perform interpretation and will generally exclude anatomical
regions requiring specialist radiological evaluation.
With CBCT, as with all digital radiographic systems, there is
broad latitude for exposure settings. Keeping doses ‘as low as
reasonably practicable’, in this context, means reducing
exposures to a level consistent with adequate image quality.
The challenge for clinicians is to identify the appropriate
exposure settings. Manufacturers may advise higher exposure
settings than are necessary because this will tend to improve the
aesthetics of images. Certain diagnostic tasks require a higher
level of detail than others. For example, detection of subtle root
resorption, root canals, and undisplaced root fractures will
require higher image resolution than tooth localisation. Children
will need a lower exposure than an adult for acceptable image
quality. The advice of the Radiation Protection Adviser/Medical
Physics Expert should be sought on appropriate exposure
settings to be used. It should be noted that a few CBCT
machines use an automatic exposure control (AEC).
If a CBCT machine offers a ‘high resolution’ option, it should be
recognized that this is only achieved by increasing the tube
current exposure time product (mAs) and, hence, the effective
dose. A few machines offer the option of partial rotations
(reduced number of basis images). This is essentially reducing
the exposure time and can be a convenient way for the
operator to lower doses.
There is evidence that thyroid shields are effective in reducing
dose with large FOV CBCT examinations.75, 76, 77 With limited FOV
examinations the thyroid gland should be well away from the
primary X-ray beam but a thyroid shield should be used if
available, and certainly for larger fields of view. It is more
68. Van Elslande D, Heo G,
71. Pittayapat P, Limchaichana73. Ludlow JB, Timothy R,
Flores-Mir C, Carey J,
Bolstad N, Willems G,
Walker C, Hunter R,
Major PW (2010)
Jacobs R (2014)
Benavides E, Samuelson DB,
Scheske MJ (2015)
Three-dimensional cephalometric
Accuracy of mesiodistal root
analysis in orthodontics: a
Effective dose of dental CBCT angulation projected by conesystematic review
a meta analysis of published
beam computed tomographic
data and additional data for
Orthodontic & Craniofacial
panoramic-like images
Research 17, 69-91
nine CBCT units
American Journal of Orthodontics
and Dentofacial Orthopedics
Dentomaxillofacial Radiology
72. Holroyd JR, Gulson AD (2009)
137(4 Suppl), S94-9
44, 20140197
The radiation protection
69. Bouwens DG, Cevidanes L,
implications of the use of dental 74. Nemtoi A, Czink C, Haba D,
Ludlow JB, Phillips C (2011)
Gahleitner A (2013)
cone beam Computed Tomography
(CBCT) in Dentistry – What you
Comparison of mesiodistal root
Cone beam CT: a current
need to know. Chilton: Health
angulation with post treatment
overview of devices
Protection Agency
panoramic radiographs and coneDentomaxillofacial Radiology
beam computed tomography
https://www.gov.uk/government/
42, 20120443
uploads/system/uploads/
139, 126-32.
attachment_data/file/421884/
70. Hodges RJ, Atchison KA,
The_Radiation_Protection_ Implications_
White SC (2013)
of_the_Use_of_Cone_Beam_Computed_
Impact of cone-beam computed
Tomography_in_Dentistry_for_
tomography on orthodontic
website.pdf
diagnosis and treatment planning
American Journal of Orthodontics
and Dentofacial Orthopedics
143, 665-74
23
ORTHODONTIC RADIOGRAPHS
12
RADIOGRAPHY IN ORTHODONTIC
TEACHING, RESEARCH AND AUDIT
important in children and young people, as the thyroid is more
likely to be close to the primary beam and to secondary
(scattered) radiation. Care should
be taken, however, to avoid the shield intruding into the primary
beam. There is no need to use abdominal protection (‘lead
aprons’) for CBCT examinations.78
All practitioners with CBCT equipment should ensure that the
Radiation Protection Adviser/Medical Physics Expert has been
consulted about appropriate clinical exposure factors for their
CBCT machine. At the time of writing, a national Diagnostic
Reference Level (DRL) has yet to be established but ‘achievable
dose’ levels for adult and child CBCT examinations, based on
dose-area-product measurement (mGy.cm2), have been set in the
UK as a guide to what is considered ‘reasonably achievable’.
The Radiation Protection Adviser/Medical Physics Expert
should establish local DRLs for individual machines for typical
examinations. Doses given to patients should be recorded and
audited in conjunction with the Medical Physics Expert at least
once every three years. Some machines provide a dose-areaproduct readout but where this is not available the actual
exposure settings used should be recorded. For further
information, national guidance should be consulted.78
TABLE 9: Strategy for optimisation: low dose protocol
When planning a CBCT examination:
l
l
l
Assess patient size and be prepared to adjust exposure factors accordingly
Select the smallest field of view consistent with the diagnostic task
Consider the diagnostic task in question and whether there is a need for
high levels of detail
Make a final choice on exposure factors
REPORTING OF CBCT
Under IRMER, the employer must ensure that all tasks in radiology
are performed by persons who have adequate training. The clinical
evaluation (‘reporting’) of CBCT scans is one such task that must
be performed and for which a written record must be kept.
THE use of radiographs in research is incorporated
in IRMER.82
All clinical research involving ionising radiation must be
reviewed by a Research Ethics Committee (REC). Details of
ethics committees are given on the National Research
Ethics Service (NRES) website.83
In a formal orthodontic postgraduate training programme
appropriate records for teaching and research are needed.
Lateral cephalometric radiographs may be necessary in order
to quantify changes, which may have occurred as a result of
growth and treatment. In selected cases additional images
may be required towards the end of active treatment and
occasionally after completion of retention.
If radiographs are taken for research purposes, and are in
addition to the normal clinical requirements, they must form
part of a properly constructed audit or research project,84 or
conform to nationally agreed standards, for example the
Clinical Standards Advisory Group (CSAG) protocols for the
long term follow up of patients with cleft lip and palate.85
A favourable ethical opinion does not replace the statutory
requirement for exposures to be individually justified by
IRMER Practitioners under current legislation (see paragraph
3.22 of reference 82), full details of which are available.86
Local rulings vary, but in many cases formal approval will be
deemed to be unnecessary where the research is retrospective
using existing records and where there is no intention of
recalling patients for further examination or investigation.
Practitioners who are not working in a teaching environment
but wish to undertake research that necessitates additional
radiographs should also seek approval from their local district
ethics committee.
Because the technology of CBCT is relatively new, interpretation
of the scans is not included in the undergraduate curriculum or as
part of specialist orthodontic training. Thus, practitioners using
CBCT as part of their practice need either to undergo additional
training or ensure that CBCT scans are reported by another
person who has adequate training.
It is feasible for dentists, through further training, to build on their
existing skills and become able to interpret small FOV CBCT
examinations of the dento-alveolar region. This region has been
defined as the teeth and their supporting bone, including the
mandible and the maxilla up to the floor of the nose.78 Curricula
for further training for dentists undertaking radiological interpretation of CBCT have been established.78, 79 Large FOV CBCT
scans extend to include regions of the head and neck outside the
dento-alveolar region (e.g., base of skull) and in such cases the
reporting should be performed by a specialist dental and
maxillofacial radiologist or a clinical (medical) radiologist.78, 79, 80, 81
This is particularly relevant for orthodontists using large FOV CBCT.
24
Where orthodontic patients are referred to an external provider of
CBCT services, there needs to be clarity about who will perform
the clinical evaluation (report). Some providers will offer a
specialist reporting service in addition to providing the scan
images. When this option is not chosen by the referrer, an
alternative arrangement needs to be arranged to satisfy IRMER.
UK guidance deals with this in greater detail.78
75. Tsiklakis K, Donta C, Gavala S,
Karayianni K, Kamenopoulou V,
Hourdakis CJ (2005)
Dose reduction in maxillofacial
imaging using low dose Cone Beam CT
European Journal of Radiology
56, 413-7
76. Qu XM, Li G, Sanderink GC,
Zhang ZY, Ma XC (2012)
Dose reduction of cone beam CT
scanning for the entire oral and
maxillofacial regions with thyroid
collars
Dentomaxillofacial Radiology
41, 373-8
79. European Commission (2012)
Cone beam CT for dental and
maxillofacial radiology
(Evidence-based guidelines).
Radiation Protection no 172.
Luxembourg: Publications
Office
http://www.sedentexct.eu/files/
radiation_protection_172.pdf
80. Horner K, Islam M, Flygare L,
Tsiklakis K, Whaites E (2009)
Basic principles for use of
dental cone beam computed
tomography: consensus
guidelines of the European
Academy of Dental and
Maxillofacial Radiology
Dentomaxillofacial Radiology
38, 187-95
77. Hidalgo-Rivas A, Davies J,
Horner K, Theodorakou C (2014)
Effectiveness of thyroid gland
shielding in dental CBCT using a
paediatric anthropomorphic phantom 81. Brown J, Jacobs R, Levring
Jäghagen E, Lindh C, Baksi G,
Dentomaxillofacial Radiology
Schulze D, Schulze R (2014)
24, 336-48
European Academy of
78. HPA Working Party on Dental Cone
DentoMaxilloFacial Radiology.
Beam CT Equipment (2010)
Basic training requirements for
Guidance on the Safe Use of Dental
the use of dental CBCT by
Cone Beam CT (Computed
dentists: a position paper
Tomography) Equipment. Chilton:
prepared by the European
Health Protection Agency
Academy of DentoMaxilloFacial
https://www.gov.uk/government/
Radiology
uploads/system/uploads/attachment_
Dentomaxillofacial Radiology
data/file/340159/HPA-CRCE-010_
43, 2013029182.
for_website.pdf
82. Health and Safety
Legislation (2000)
The Ionising Radiation
(Medical Exposure)
Regulations 2000.
SI 2000 No 1059. London,
the Stationery Office
(IRMER)
http://www.legislation.hmso.
gov.uk/si/
si2000/20001059.htm
83. National Research Ethics
Service
http://www.hra.nhs.uk/
about-the-hra/ourcommittees/nres/
84. Smith NJ (1987)
Risk assessment: The
philosophy underlying
radiation protection
International Dental Journal
37, 43-51
85. Clinical Standards Advisory
Group (1998)
Report of a CSAG Committee
on cleft lip and/or palate.
The Stationery Office,
London
86. Central Office for Research
Ethics Committees
http://www.corec.org.uk
ORTHODONTIC RADIOGRAPHS
13
IMAGING OF THE
TEMPOROMANDIBULAR JOINT
BOTH general practitioners and orthodontists will encounter
patients with a range of temporomandibular joint (TMJ)
disorders. Modern imaging of the TMJ is dependent on facilities
available and the suspected underlying disease based on the
patients clinical signs and symptoms. Imaging could include:
• Conventional panoramic radiography
• Specific field limitation TMJ panoramic programmes
• Transpharyngeal radiography
• Multidirectional tomography
• Cone beam computed tomography (CBCT)
• Computed tomography (CT)
• Magnetic resonance (MRI).
The main pathological conditions that can affect the
TMJ include:
• TMJ pain dysfunction syndrome (myofascial pain
dysfunction syndrome)
• Internal derangements
• Osteoarthritis (degenerative joint disease)
• Rheumatoid arthritis.
It has been argued that the absence of pre-treatment
radiographs could be considered negligent when TMJ pain
dysfunction symptoms develop during or after orthodontic
treatment. Conventional radiographs are no longer
recommended for investigating TMJ pain dysfunction so the
need to have any radiographs taken in advance of treatment in
order to avoid possible later claims of negligence cannot be
justified.93 There have been suggestions that orthodontic forces
or the extraction of teeth, as a part of orthodontic treatment,
can cause symptoms of TMJ pain dysfunction. However, there is
ample evidence to refute these suggestions and in an extensive
review of the literature Luther suggested that ‘neither
possession of malocclusion nor orthodontic treatment can be
said to cause or cure TMJ pain dysfunction’.94, 95
In patients suspected of having disease affecting the bones of
the TMJ, conventional radiographs, particularly panoramic
radiographs, are still only of limited value. These patients could
possibly benefit from CBCT imaging but only if the additional
information obtained is likely to influence management or
subsequent treatment.
The advice remains to take an adequate history and to examine
the patient fully before starting orthodontic treatment.96
TMJ (myofascial) pain dysfunction syndrome is the most
common clinical diagnosis applied to patients with pain in the
muscles of mastication, often worse in the morning or evening,
with occasional clicking and stiffness. The aetiology is said to
include malocclusion, bruxism, trauma and psychological factors.
Symptoms may develop during orthodontic treatment
particularly if there is evidence of subclinical problems at the
start.87 The bony components of the TMJ – the condylar head
and the glenoid fossa – are usually normal so conventional
imaging is of limited value.88, 89 The Royal College of Radiologists
state that in relation to TMJ dysfunction, radiographs ‘do not
add information as the majority of these temporomandibular
joint problems are due to soft tissue dysfunction rather than
bony changes, which appear late and are often absent in the
acute phase’.90
Whilst it has been common practice to take conventional
radiographs of the joints in patients with TMJ pain dysfunction,
this practice can no longer be justified and is therefore
no longer recommended.
Treatment for the majority of patients with TMJ pain dysfunction
that will be encountered in orthodontic practice in most cases is
conservative and will include reassurance, exercises or the fitting
of biteguards. This treatment would not be altered in anyway as
a result of radiographic findings, hence the recommendation
that radiographs are not required.91
Although much attention is given to the position of the disc
within the TMJ, the disc cannot be visualised directly on
conventional radiographs or on CBCT. Satisfactory soft tissue
images can be obtained using MRI which does not use ionising
radiation. However, abnormal position of the disc does not
necessarily equate with disease – research using MRI has shown
altered disc position in over 30% of symptomless volunteers.92
MRI imaging of the TMJ is generally reserved for those patients
with persistent symptoms following conservative treatment when
surgical intervention is being considered.
87. Ruf S (2005)
TMD and the daily
orthodontic practice
World Journal of Orthodontics
6 (Suppl), 210
88. Petrowkski CG (1999)
Temporomandibular Joint.
In Oral Radiology –
Principles and Interpretation.
White SC and Pharoah MH.
4th Edition, Mosby: St Louis
90. iRefer (2012)
Making the best use of Clinical
Radiology. 7th Edition, Royal
College of Radiologists
91. Eliasson S and Isacsson G
(1992)
Radiographic signs of
temporomandibular disorders
to predict outcome of
treatment
Journal Craniomandibular
Disorders 6, 281-7
89. Brooks SL, Brand JW,
92. Kircos LT, Ortendahl DA,
Gibbs SJ, Hollender L,
Mark AS, Arakawa M (1987)
Lurie AG, Omnell KA,
Magnetic resonance imaging of
Westesson PL, White SC
the TMJ disc in asymptomatic
(1997)
volunteers
Imaging of the temporoJournal of Oral and
mandibular joint. A position
Maxillofacial Surgery
paper of the American
45, 852-4
Acadamy of Oral and
Maxillofacial Radiology
Oral surgery
Oral Surgery, Oral Medicine,
Oral Pathology, Oral Radiology
and Endodontics 83, 609-18
93. Atchison KA, Luke LS, White SC
(1992)
An algorithm for ordering
pre-treatment orthodontic
radiographs
American Journal of Orthodontics
and Dentofacial Orthopedics
102, 29-44
94. Luther F (1998)
Orthodontics and the
temporomandibular joint: where
are we now? Part 2. Functional
occlusion, malocclusion and TMD
The Angle Orthodontist
68, 305-18
95. Williams P, Roberts-Harry D,
Sandy J (2004)
Orthodontics. Part 7: Fact and
fantasy in orthodontics
British Dental Journal,
196, 143-8
96. Davies SJ, Gray RM, Sandler,
PJ, O’Brien KD (2001)
Orthodontics and occlusion
British Dental Journal
191, 539-49
25
14
MEDICO-LEGAL ASPECTS OF
RADIOGRAPHY FOR ORTHODONTIC
PURPOSES
NEED FOR RADIOGRAPHY
The International Principles of Ethics for the Dental Profession
formulated by the Federation Dentaire Internationale (FDI) state
‘The primary duty of the dentist is to safeguard the health
of patients...’97
The clinical decision about the need for radiography is influenced
by many factors. It is unethical to take radiographs for medicolegal, administrative reasons or ‘just in case’ if there is no
clinical need. It has been stated by the Royal College of
Radiologists that ‘if, as a result of careful clinical examination,
you decide that an X-ray is not necessary for the future
management of the patient, your decision is unlikely to be
challenged on medico-legal grounds.’ 98
It is the legal responsibility of all clinicians to be aware of all
relevant current legislation relating to radiography.
STORAGE AND RETENTION OF RADIOGRAPHS
Radiographs are a diagnostic aid that form part of a patient’s
clinical records. The Data Protection Act (1998)99 entitles
patients to see their clinical records whether in computerised
or manual form.
Whilst patients are legally entitled to copies of their records
it is important that the practitioner retains the original
records.100, 101
The ownership of records can be summarised as:
• NHS General Dental Services records should be considered to
be the property of the individual orthodontist or primary care
organisation, although NHS authorities have certain rights of
access to these records
The European Union Directive on Data Protection106 specifies
that data must be obtained and processed fairly and lawfully,
held and processed only for specified, explicit and legitimate
purposes. This directive also outlines the need for ethical
approval and individual consent for research and audit purposes.
Transfer of radiographs
When a patient is referred to a specialist for orthodontic
treatment or opinion the relevant radiographs and clinical
information must be forwarded.107
If the images are retained for the duration of orthodontic
treatment and subsequent monitoring, the orthodontist must
ensure the safe storage of the radiographs to comply with
current recommendations for the retention of records. This will
necessitate liaison with the original referring clinician. Clearly,
the availability of digital radiology facilitates copying of images
and transfer when required.
Good records are often critical in refuting allegations of
negligence. Defence may prove impossible if:
• Radiographs were not taken when there were justifiable
clinical grounds for doing so
• Radiographs have been lost
• Radiographs that have been taken are of such poor quality
that they are of little or no clinical use or diagnostic value
• Radiographs are not reported or interpreted correctly
• Radiographic reports are not retained as part of the patient
health record.
• Private patient records are the property of the individual
practitioner but the legal position with regard to ownership
of radiographs is uncertain and to date has never been
tested in law. 102
• Records should be kept for 10 years after completion of
treatment and those relating to children should be kept until
the patient’s 25th birthday, or 26th if an entry was made
when the person was 17 years old.
The recommended time to retain records for legal purposes is
complex and for England and Wales the principle guidance is
contained in Records Management: NHS Code of Practice.103
The Consumer Protection Act (1987)104
• A patient is entitled to compensation if damaged by a
defective product. It is not necessary to demonstrate
negligence. An action arising from this Act (Injury from
Defective Product) may occur 10 years after the knowledge of
such an episode. It would therefore seem wise to arrange to
retain radiographic records until 11 years after the last record
entry (making a one year allowance for the due process of
law), or 25 years of age, whichever is the longer
• Some Defence and Protection organisations advise that from
a dento-legal perspective all records should be retained
indefinitely. This may prove difficult.
26
More detailed advice on record keeping is provided in the BOS
guidelines, Orthodontic Records: Collection and Management.105
100. Corless-Smith D (2000)
106. European Parliament,
Council of the European
Transfer of radiographs
questioned.
Union (1995)
British Dental Journal 188, 293
Directive 95/46/EC of the
European Parliament and of
101. Hirshman PN (1999)
the Council of 24 October
Transfer of radiographs
1995 on the protection of
British Dental Journal 187,463-4
individuals with regard to
102. MDU Journal (1995)
the processing of personal
98. Royal College of Radiologists
11, 43
data and on the free
(2003)
movement of such data.
103. Department of Health (2006)
Making the best use of a
Official Journal of the
Department of Clinical Radiology:
Records Management: NHS
European Communities
Guidelines for Doctors. 5th Edition.
Code of Practice. London, HMSO
281,
31–50
London, Royal College of
https://www.gov.uk/government/
Radiologists
publicationrecordsmanagement- 107. Health and Safety
Legislation
(2000)
nhs-code-ofpractice
99. HM Government (1998)
The Ionising Radiation
Data Protection Act. London,
104. HM Government (1987)
(Medical Exposure)
HMSO
Consumer Protection Act.
Regulations 2000.
http://www.legislation.gov.uk/
London, HMSO
SI 2000 No 1059. London,
ukpga/1998/29/contents
http://www.legislation.gov.uk/
the Stationery Office (IRMER
ukpga/1987/43/contents
http://www.legislation.hmso.
105. Clinical Governance
gov.uk/si/si2000/20001059.
Directorate, British
Orthodontic Society (2015)
Orthodontic Records: Collection
and management. London,
British Orthodontic Society
97. FDI (1997)
International principles of ethics
for the dental profession.
Federation Dentaire Internationale
http://www.fdiworldental.org/
media/11263/
Internationalprinciples-of-ethicsfor-thedental-profession-1997.pdf
ORTHODONTIC RADIOGRAPHS
15
CONCLUSIONS
GOOD quality radiographs provide a valuable record to
assist in the assessment and management of malocclusion,
clinical audit, and research.
Many of the suggestions in this document are a matter of
common sense. For example, avoiding repetition of recent
images, being satisfied that there is a clinical need before
requesting a radiograph, or making use of other less
invasive procedures.
Radiographic exposure is an invasive procedure. It is
appropriate to seek a sensible risk/benefit balance in its use
for orthodontic purposes. This requirement is particularly
relevant to the use of CBCT in orthodontics.
These Guidelines should not be interpreted as absolute rules,
but rather are offered to provide help in an area of clinical
practice where attitudes are changing rapidly. For guidelines to
serve a useful purpose they must be monitored and updated in
line with current practice, developments and legislation. It will
be important for both clinicians and the British Orthodontic
Society to keep this balance under review, as has been
attempted with this 4th Edition.
Clinicians should note:
examination, when it is deemed to provide sufficient
benefit to the exposed individual and will influence
clinical management
• All radiographs should be evaluated (reported)
facial growth
• Radiographs of the hand and wrist to predict the onset of
the pubertal growth spurt
• Radiographs for investigation of temporomandibular disorders
associated with TMJ (myofascial) pain dysfunction
• Prospective radiographs only for medico-legal reasons
i.e., the practice of ‘defensive dentistry’
• Post-treatment radiographs for professional examinations
and clinical presentation
• Routine Cone Beam CBCT for all orthodontic patients.
THE ESSENCE OF THESE
GUIDELINES IS:
Take radiographs
ONLY
when justified
clinically
›
• A radiograph should only be taken after a clinical
• Radiographs before a clinical examination
• Radiographs when only minimal tooth movement is planned
• Full mouth periapical views before treatment
• A cephalometric lateral radiograph for the prediction of
›
In summary, careful assessment and the justification of
need for a radiographic examination, meticulous technique,
quality assurance and understanding the advantages and
disadvantages of the different imaging techniques available,
are the keys to the best clinical practice of radiography
in orthodontics.
There is no indication for the following practices of
taking or requesting:
This is a legal
requirement in
the UK
and this evaluation should be recorded
• There is no known safe level of radiation exposure
• The benefits of diagnostic radiology generally
outweigh the risks
• The level of risk is only justified when the patient
receives a commensurate health benefit from
a minimum dose.
There is little evidence to support the use of
radiographs for the following practices:
• Monitoring the developing occlusion
• Assessing a patient who is likely to be placed on a
waiting list for treatment
• Evaluating post-treatment occlusal changes.
27
16
GLOSSARY
AEC
Automatic exposure control
ALARP
As low as reasonably
practicable
BAOMS
BOS
British Association of Oral and
Maxillo-Facial Surgeons
British Orthodontic Society
BSDMFR British Society of Dental and
Maxillofacial Radiology
FGDP(UK) Faculty of General Dental
Practice (United Kingdom)
PSP
Photo-Stimulable Phosphor
plate
FOV
Field of view
QA
Quality Assurance
FSD
Focus to skin distance
REC
Research Ethics Committee
GDC
General Dental Council
RPA
Radiation Protection Advisor
HMSO
Her Majesty’s Stationery
Office.
RPS
Radiation Protection
Supervisor
HSC
Health Service Circular
SIGN
HSE
Health and Safety Executive
Scottish Intercollegiate
Guidelines Network
TMD
Temporomandibular Joint
Disorder
TMJ
Temporomandibular Joint
WHO
World Health Organisation
BSSO
British Society for the Study of
Orthodontics
CBCT
Cone Beam Computed
Tomography
ICRP
International Committee on
Radiological Protection
CCD
Charge-coupled device
IRMER
Ionising Radiation (Medical
Exposure) Regulations 2000
CMOS
Complementary Metal Oxide
Semiconductors
IRR
Ionising Radiations
Regulations 1999
COSHH
Control of Substances
Hazardous to Health
MRI
Magnetic Resonance Imaging
CPD
Continuing Professional
Development
NCRP
National Committee on
Radiological Protection
CSAG
Clinical Standards Advisory
Group
NRES
National Research Ethics
Service
CT
Computed Tomography
NRPB
National Radiological
Protection Board
DCP
Dental Care Professional
PACS
DRL
Diagnostic reference level
Picture Archiving and
Communication System
FDI
Federation Dentaire
Internationale
28
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